Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.

The 1st link has Gemtech-style slanted baffles. The 2nd is a more traditional monocore with curved baffles.
They are both made from 7075 Aircraft Grade Aluminum with 1/2-28 or 5/8-24 threads. So limited to rimfire use only.
I still have some F1 stamps left that I've never used. So I thought of engraving the tube on one of these.
My question is: since they have probably done zero dB meter testing, which would be the better design for my Ruger 10/22? It's 16.5" bbl with 1/2"x24 thread if that matters.

And I plan to use mainly Remington Subsonics or cheap 60 gr lead round nose.

The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
Well I AM 1/16 Demon on my Father's Side!-Dresden Files

Yes, they post that the openings are .400" so that would be 13/32".
I don't know how straight the threads are aligned, so I figured that maybe a looser boreline would help reduce baffle strikes.
Does the size of the bore holes really matter that much for .22lr? I've heard .5L plastic bottles where the bolt cycling was louder than the muzzle blast (1m behind the shooter.)

I thought about just using the UPC plastic bottle adapter with the Mnfr Info engraved upon it. I don't know it those are still legal or if ATFE has reversed their Ruling on that. I heard that the bottle is no longer ruled as "fungible" as a wipe. I don't know how this affects Users who have already purchased their Tax Stamp on these? Were they grandfathered, or had to be destroyed/turned in to ATF?

The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
Well I AM 1/16 Demon on my Father's Side!-Dresden Files

I posted to that person on the forum that you mentioned T-rex. It seems that he is no longer answering his PMs. Seems that ATF may have shut him down for "sharing info and vids created by OTHER people."

It's a pity, his products seemed really good and he said that he was expanding to Ti and 1.5" OD tubes. Hopefully I'll hear from him soon.

Otherwise, does the tightness of the bore holes really matter much on .22lr? Like I said, I've heard good results on .5L bottles. So I'm looking for input on which of these options would be best for both performance, and also not being ruled a no-no by ATF in the near future....

The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
Well I AM 1/16 Demon on my Father's Side!-Dresden Files

Seems that ATF may have shut him down for "sharing info and vids created by OTHER people."

Clarification of this? Why would the ATF care about videos?

As I understand, AFT threw a hissy fit that those making Solvent Traps were posting instructions, of how those who LEGALLY get permission from ATF via a Form1 Tax Stamp MAY wish to alter the parts to create openings for fluid (or projectiles) to pass through. They claimed that this violated their Admin Rulings and Policy (not Legislation) that makers weren't to inform others how to modify parts (thus making each a "silencer part" requiring separate tax stamps and making the parts illegal to transfer without all of the additional SOT, 7/02, Class 3-Dealer, etc steps in the process.)

It's just another way for the Deep State to screw with the People and violate our Constitution and the Law.

The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
Well I AM 1/16 Demon on my Father's Side!-Dresden Files

Hmm I haven't heard or read anything, regarding anything even close to that.

But, back to the design.
No, I don't think that giant bore would do well for 22lr, w/ or w/o a wipe.
The G-core does a decent job, but not better than 60deg cones in the same size design.
The Chinese copy may be close, but isn't exact, and it's not as long as what would be in a mist barrel.
Coupled w/ the large bore, easy pass.

Those cheap filter kits, that come with 60deg cups, can be made into a quite efficient product.
Read ECCO's thread, here.

I have no idea about the vids. I only parroted what they posted on that Thread that you listed.

Update: xrttactical replied to my PM and he is still taking orders for a planned Production Date of 2 months from now with a larger Selection of sizes and Options.
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I've been away from the "F1 World" for awhile. What was the proposed Application for the Gemtech Design? .30 Supers? .45 ACP? I recall that they were a variation on the Slanted Sidewall Concept.

I recall now that the surefire Ryder22 was the "cutting edge in design" for low pressure applications. The "pig snout" Feature and indexed tabs to prevent rotation. Is this still the best design?
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Thank you greatly for your link to the ECCO machine review of Kits. Very helpful and informative.

I'm thinking about buying 1 of his kits, but they are a bit pricey. I'll probably PM him for a quote since he is planning another run of 1"ODx3"L kits. Hopefully he can make a 6.5"L with Surefire "Pig snout" type cups.

I'll keep you posted, but will keep our price negotiation confidential.
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Again, great to talk to you T-Rex

The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
Well I AM 1/16 Demon on my Father's Side!-Dresden Files

This seems to have larger volume, better baffle design (spiral-fluted cones with mouse-holed, coaxial skirt.) Plus no bore openings. So I can use ~.25" or 5/16" drill bit. (As opposed to the .400" bore of their monocore models.)